1. Field
This invention relates to objects towed by traction vehicles. It particularly relates to the accurate backing of such towed objects.
2. State of the Art
Steering a vehicle while backing up with an attached trailer is an acquired skill. Even individuals with considerable driving experience often have little occasion to develop the skills required to back a trailer. Drivers are generally frustrated with backing, particularly when the backing is done primarily with the use of mirrors. Much of the difficulty associated with backing a trailer results from the inherent positive feedback that occurs when backing.
A towing vehicle or powered component of an assembly will be referred to in this disclosure as a "tractor component." A towed object or vehicle will be referred to as the "trailer component." For simplicity, the assembly will be regarded as a "tractor-trailer assembly," even though the respective components may be otherwise identified in common parlance. For example, an automobile or truck may be regarded as a "tractor" while a cannon, if towed, might be regarded as a "trailer."
The difference between the respective directions of travel of the tractor and trailer components of the assembly may be referred to as the "ball angle." When backing (traveling in the reverse direction) with any fixed steering position, the ball angle will inevitably continue to change. In fact, the ball angle continues to change at an increasing rate per foot traveled, until the components of the assembly jackknife.
"Jackknife" is the condition in which the hitched truck and trailer collide with each other because of an excessive ball angle. This jackknife condition will always occur with any fixed steering position and continued backing.
Long distances can be driven in the forward direction with only a slight amount of steering. However, when backing a trailer, there is a constant need for corrective steering. Otherwise, a jackknife situation will occur. Hence, backing a trailer creates an inherently changeable situation that requires frequent corrective steering.
Accurate backing represents a challenge to most drivers. Yet, there has been little improvement in the equipment available to guide steering of a tractor backing a trailer. There remains a need for a manual or automated computer assisted steering system whereby backing can become a relatively simple procedure.